Experimental study on liquid piston Stirling engine combined with self-rectifying turbine.

<div class="htmlview paragraph">The Fluidyne, or liquid piston stirling engine, has many characteristics which make its use in developing nations particularly attractive. Besides being compatible with the use of lowgrade heat sources, the machine is simple to manufacture using a variety of low cost materials and is exceedingly reliable.</div> <div class="htmlview paragraph">This paper uses a summary of fluidyne experience to evaluate applications of the fluidyne to water pumping requirements in developing countries for purposes including domestic, livestock, and irrigating uses for water pumping. Possible sources of energy are evaluated in the light of availability and needs. Environmental, economic, and social benefits are also examined. Particular applications of the fluidyne to existing situations in China are evaluated in detail.</div>

Boiling is an effective and critical energy transfer process in energy, aerospace, and electronic applications. With the rapid development of nanotechnologies, the development of a highly efficient thermal management system for high flux energy applications from microscale to nanoscale becomes a promising topic. The dissolved air in water nanofilms has adverse influence on the boiling process due to the size effects, but the boiling mechanism at the nanoscale has not been well clarified. Therefore, non-equilibrium molecular dynamics (NEMD) simulations are employed to investigate the behavior of water boiling on a nanoscale copper surface in the presence of air. We observe that the interfacial air layer adsorbed on the copper surface increases the boiling time by 73, 20, and 7 times at a pressure of 1bar, 20bar, and 100bar, respectively. We propose a theoretical model based on the heat conduction differential equation to predict the time evolution of water temperature at atmospheric pressure. The results indicate that the boiling process at the nanoscale only manifests into Leidenfrost phenomenon rather than bubble nucleation, along with the negative effects of air dissolved in water nanofilm. By revealing the boiling process on a copper surface at the nanoscale, this work provides useful insights for broad applications in nanoscale thermal management and energy conversion.

In a multi-cylinder type liquid piston Stirling engine (MCLPSE), liquid columns in U-shaped tubes play the role of solid pistons in a mechanical Stirling engine. Besides the straightforward structure, advantages of the MCLPSE are a relatively low operation temperature difference below 100 K and use of harmless working fluids of air and water. This study presents a mass spring model for the MCLPSE, from which we determine geometrical parameters of MCLPSE to achieve a target acoustic power production under a given temperature condition. The preliminary test results will be presented.

The production of metal nanoclusters composed of less than 103 atoms is important for applications in energy conversion and medicine, and for fundamental studies of nanomaterial nucleation and growth. Unfortunately, existing synthesis methods do not enable adequate control of cluster formation, particularly at atmospheric pressure wherein formation typically occurs on sub-millisecond timescales. Here, we demonstrate that ligand-free, unagglomerated nickel nanoclusters can be continuously synthesized at atmospheric pressure via the decomposition of bis(cyclopentadienyl)nickel(II) (nickelocene) in a spatially-confined microplasma process that rapidly quenches particle growth and agglomeration. The clusters were measured on line by ion mobility spectrometry (IMS) and further analyzed by atomic force microscopy (AFM). Our results reveal that stable clusters with spherical equivalent mean diameters below 10 are produced, and by controlling the nickelocene concentration, the mean diameter can be tuned up to ∼50 . Although diameter is often the sole metric used in nanocluster and nanoparticle characterization, to infer the number of atoms in AFM and IMS detected clusters, we compare measured AFM heights and IMS inferred collision cross sections to theoretical predictions based on both bulk matter approximations and density functional theory and Hartree–Fock calculated Ni nanocluster structures (composed of 2–15 atoms for the latter). The calculations suggest that Ni nanoclusters composed of less than 102 atoms can be produced repeatably with simple microplasma reactors.

The aim of the work is to develop an energy-saving device that provides the conversion of thermal energy into electrical energy. The design and materials of the thermoelectric converter unit, consisting of 12 thermoelectric converter modules, a cooling radiator and a switching unit, were developed and selected. Based on the test results, the zone of the maximum temperatures in the section of the gas duct recommended for the installation of a gas cooling module using a thermoelectric converter was determined. The technology for cooling gases with the help of a thermoelectric converter was tested on the site located in front of the experimental heat exchanger. An assessment of the efficiency of the conversion of heat into electrical energy was conducted using the design of the thermoelectric converter unit, based on thermoelectric modules TGM 127-1.4-1.2. It was determined that the device is capable of generating electricity stably for production needs. The data obtained showed that, at a temperature difference of 75-80 °C between the wall surface of the gas duct section and the coolant, the power of one thermoelectric converter block of the gas cooling system reaches 9 W.

This paper addresses modeling, design, and experimental assessment of a Gamma type low-temperature differential free-piston Stirling engine. The most advanced third-order design analysis method is used to model, simulate and optimize the engine. Moreover, the paper provides an experimental parametric investigation of engine physical parameters and operating conditions on the engine performance. The experimental test results are presented for a model validation, which shows about a 5% to 10% difference in the simulation results. The aim of this study is to design a Stirling engine capable of harvesting low-temperature waste heat effectively and economically and convert it to power. The engine prototype is designed to increase the engine performance by eliminating the main losses occurred in conventional Kinematic engines. Thus, elastic diaphragm pistons are used in this prototype to eliminate the surface friction of the moving parts, the use of lubricant, and to provide appropriate seals. In addition, flat plate heat exchangers, linear flexure bearing, a stainless-steel regenerator and a polyurethane displacer are outlined as the main components of the engine. Experiments successfully confirm the design models for output power and efficiency. Furthermore, it is revealed that the displacer-to-piston natural frequency ratio is an important design point for free-piston Stirling engines and should be addressed in the design for optimum power output.

A project of electrical rocket engine of the future, which operates on principle of a magnetoplasmadynamic engine, is being considered. New concept of the superconducting magnetic system, stipulating installation of external field winding, in which the current is directed parallel to longitudinal axis of the engine, makes it possible to increase the magnitude of the transversal magnetic field in working chamber, to decrease the rated current and to raise the engine efficiency. On the basis of equations that describe the process of converting electrical energy into mechanical energy, a mathematical model has been composed with whose help the characteristics of magnetoplasma engine having conventional design and the characteristics of the engine being developed in the project have been determined. Conducted research has shown that new design increases engine efficiency from 50% up to 91%. The project also contains a consideration of the new engine design with movable cathode and with cathode having forced cooling which helps to reduce carryover of cathode mass and to increase lifetime by several times. In conclusion, the results of calculations and constructive development of electrorocket engine for flight towards planet Jupiter, which creates tractive force of 250 N at 2500 kW power, are given.

SOLARBALL: Extremly light, efficient and low-cost solar cooker

This chapter discusses the application of ultrahigh temperature thermal energy storage (TES) and conversion to spacecraft systems. The use of silicon and boron as phase change materials (PCMs) is of primary interest for spacecraft in the context of a thermal rocket. The history of this concept is discussed as applied to solar thermal propulsion and dual-use radioisotope propulsion and power systems. In both the cases the use of high-temperature PCMs as a primary thermal capacitor has been frequently cited as beneficial, but investigations seldom go beyond the conceptual phase. For solar thermal propulsion, the inclusion of PCMs can drastically decrease the volume and mass of a propulsion system, provided that effective convective coupling to the PCM is achieved in the heat exchanger. However, the benefits of solar thermal propulsion have historically been relegated to niche mission scenarios. The more compelling application of ultrahigh temperature PCMs is in a pulsed radioisotope propulsion and power system where it is a truly enabling technology offering both high specific energy and power. It is suggested that future development efforts would focus on characterizing convective coupling to a latent heat storage medium since all applications require some form of heat exchange with a working fluid. A meaningful mission design cannot just look at material properties and must include effective energy transfer for an optimized heat exchanger to determine the net system benefit. Ultimately, this chapter highlights benefits that can be obtained by latent heat TES but cautions that the ultimate benefit to a spacecraft system is mission-dependent and will rely on a distinct mission need for a high specific power and energy system to justify technological investment.

ABSTRACTEmerging black phosphorene (BP) has unique advantages in mediating near-field thermal radiation due to its strong and tunable in-plane anisotropy, but relative researches are rarely reported in stark contrast to its gained tremendous attention in other fields. Here, we investigate near-field thermal radiation of nanopatterned BP considering different ways of patterning and electronic doping. Appropriate doping increases free carrier density, enabling the transition of BP from dielectrics to hyperbolic materials and the excitation of plasmon resonances. Nanopatterned BP is found to possess a higher radiative transfer rate by as high as 65% compared with plane counterparts due to topological transition of phosphorene ribbon plasmons from quasi-ellipses to quasi-hyperbolas. This work opens alternative routes to mediate and enhance near-field thermal radiation, which has promising applications in efficient thermal management and energy conversion.

Catalytic systems prepared by controlled processes play an important role in the utilization of CO2 via catalytic hydrogenation to produce useful C1 chemicals (such as CO, CH4 and CH3OH), which will be vital for forthcoming applications in energy conversion and storage. Size controlled Pt nanoparticles were prepared by a polyol method and deposited on H-ZSM-5 (SiO2/Al2O3 = 30, 50, 80 and 280) zeolite supports. The prepared catalysts were tested for the CO2 hydrogenation in the temperature range of T = 473–873 K and ambient pressure, with CO2/H2 = 1:4. Size-controlled Pt nanoparticles boosted the catalytic activity of the pure H-ZSM-5 zeolites resulted in ~16 times higher CO2 consumption rate. The activity were ~4 times higher and CH4 selectivity at 873 K was ~12 times higher over 0.5 % Pt/ H-ZSM-5 (SiO2/Al2O3 = 30) compared to 0.5 % Pt/H-ZSM-5 (SiO2/Al2O3 = 280). In situ DRIFTS studies assuming the presence of a surface comlex in which the CO is perturbed by hydrogen and adsorbes via C-end on Pt but the oxygen tilts to the protons of the zeolite support.

A novel approach to environmental pollution management/remediation techniques using derived advanced materials

Developing efficient multifunctional materials for the oxygen evolution reaction (OER) and supercapacitors has become essential for storing and converting energy. Taking advantage of the structural flexibility of metal–organic frameworks (MOFs), bifunctional electrochemical nanomaterial LaFeCoOOH with high performance is successfully synthesized by doping rare earth La atoms in transition metals. La doping modifies the coordination environment of active sites and material morphology, modulates the energy structure, improves material conductivity, and optimizes the adsorption and desorption performance of oxygen intermediates. LaFeCoOOH demonstrates exceptional electrocatalytic activity for OER, achieving a remarkably low overpotential of 177 mV at 10 mA cm −2 current density in 1 m KOH alkaline electrolyte. The material exhibits outstanding operational stability, maintaining consistent performance for over 1000 h at an elevated current density of 100 mA cm −2 under identical alkaline conditions. Furthermore, LaFeCoOOH electrode displays superior electrochemical energy storage capabilities, demonstrating an impressive specific capacitance of 3508 mF cm −2 at 1 mA cm −2 current density. When configured as an asymmetric supercapacitor (LaFeCoOOH//Activated Carbon (AC)) using 6 m KOH electrolyte, the device achieves an exceptional energy density of 118.52 µWh cm −2 while delivering a power density of 1700 µW cm −2 , highlighting its dual functionality for both energy conversion and storage applications. Hence, this study provides a new perspective for the exploration of new multifunctional transition metal composites modified with rare earth elements for energy storage and conversion applications.

The performance of energy storage devices is highly related to the properties of electrode materials, such as components, morphology, configurations and so on. As a typical hierarchical carbon material, three-dimensional ordered porous carbon (3D-OPC) has unique characteristics of low cost, large specific surface area, highly ordered channels, and high electronic and ionic conductivity, which shows great potential in energy storage and conversion applications. In this mini review, we summarize various template-assisted preparation methods for 3D-OPC, including hard-, ice- and self-templated approaches, and their applications in electrocatalysis, batteries and supercapacitors. Additionally, the critical roles of vertical channels in 3D-OPC when used as electrodes are also discussed. Finally, the current challenges and future research outlook of 3D-OPC are proposed.

Single-particle spectroscopy is central to the characterization of plasmonic nanostructures and understanding of light-matter interactions in chiral nanosystems. Although chiral plasmonic nanostructures are generally characterized by their circular differential extinction and scattering, single-particle absorption studies can extend our understanding of light-matter interactions. Here, we introduce an experimental observation of photothermal chirality which originated from circular differential absorption of chiral plasmonic nanostructures. Using luminescence ratio thermometry, we identify the optical and photothermal handedness and an absolute temperature difference of 6 K under the right and left circularly polarized light. We observe a circular differential extinction parameter (gext) of -0.13 in colloidally prepared gold helicoids and compare our findings with numerical simulations using finite element methods. The simulated data showed that circular differential absorption and the maximum temperature of a small cluster of helical nanoparticles are polarization-dependent. We observed an intensity-dependent photothermal g-factor from chiral helicoids that decreases slightly at higher temperatures. We also measure a range of optical g-factors from several gold helicoids, which are attributed to the heterogeneity of helicoids in nanoparticles during synthesis. The principles of differential photothermal response of chiral nanomaterials and heat generation described here can be potentially used for thermal photocatalysis, energy conversion, and electronic applications.